The present invention refers to a device for preparation such as staining of biological samples.
The method which is commonly used for introducing contrasting material in sections of a biological specimen in electromicroscopy is a so-called double-staining in uranyl acetate and lead citrate. This staining is usually performed on drops of the staining solution in petri dishes, each section carrying grid being stained separately. In addition to the considerable amount of manual work involved when big series of sections are to be stained, the method is very sensitive to contaminations, deriving either from air born dirt particles or from different precipitates in the staining solutions or on the surface of the drop (for example lead carbonate from the reaction between lead citrate and carbon dioxide). Presumably most of the contaminations on the sections are obtained when the sections are applied on the top of the drop or when the sections are brought through the surface of the staining solution (when the grids are brought through the staining solutions). A further source of contamination is the transfer of the grids from the drop to a cleaning water bath. During this transfer, staining solution attached to the sections will be brought in contact with air. If the transfer is too slow and evaporation may occur on the surface layer, whereby precipitates of the staining solution, and/or reactions between carbon dioxide and lead citrate might give rise to contaminations on the sections. A description of these staining procedures known per se is given in the following publications:
Hayat, M. A.: Principles and techniques of electron microscopy. Biological applications, Vol. 1. Van Nostrand Reinhold comp., New York 1970, or PA1 Lewis, P. R., Knight, D. P.: Staining methods for sectioned material. Practical methods in electron microscopy Eds. A M. Glaubert, North-Holland Publishing Comp. 1977.